"The Red Cross is arranging for them to have copies of the Koran," the prime minister's spokesman added.

"They have also been provided with washing materials and calls to prayer are being broadcast over the camp public address system."

The prisoner's cells were "basic but fit" and the US military authorities had been "helpful and open throughout the visit," he said.

Pictures in the press over the weekend showing bound and gagged men were taken shortly after the suspects arrived in Cuba, the spokesman said.

The British team were there to assess their identity and welfare.

Earlier, Mr Abbasi's MP, Geraint Davies, was among Labour backbenchers expressing their worries about the way the men were being treated.

He told BBC Radio 4's Today programme: "The perception of the treatment as opposed to the real treatment is counter productive in the Muslim community."

Basic standards

There are 144 prisoners at the base, after the arrival of 34 more suspects early on Monday. The camp is eventually expected to hold more than 300 detainees.

Earlier, Foreign Secretary Jack Straw said: "The British Government's position is that prisoners - regardless of their technical status - should be treated humanely and in accordance with customary international law.

"We have always made that clear and the Americans have said they share this view."

The US - which maintains the detainees are being treated humanely - refuses to call them prisoners of war, referring to them as illegal combatants.

Under the Geneva Convention, PoWs must be tried by the same courts and under the same procedures as US soldiers.

Under that status, prisoners would be tried for war crimes through courts-martial or civilian courts, not by secretive military tribunals which could impose the death penalty.